Aircraft Maker and Unions Are Trying to Hammer Out a New Labor Agreement

Boeing Co. warned it could look to build its planned 777X jetliner outside Washington state, amid signs of union resistance to a contract that would keep the production work at the aerospace giant's traditional manufacturing base but exact labor concessions.

The Boeing statement late Thursday came after members of the International Association of Machinists and Aerospace Workers, which represents about 33,000 Boeing employees, met with their union leaders in Seattle to discuss the proposed contract from Boeing. That...